Solar Filters by Seymour SolarThis premium solar filter is safe to photograph or view the sun when mounted on a telescope, view finder, spotting scope, etc. It is rated ND5 so 99.999% of the sunlight is blocked. The aperture is made of a high quality, reflective coated, Helios Solar Glass, and mounted into an aluminum outer cell. The filter slips over the sky end of your optical tube. It is secured and centered to the optical tube with thumb screw(s) and felt tabs.